
<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<div id="content">
    <div id="linefirst">This is first line</div>
    <div id="line2">This is line 2</div>
    <div id="line3">This is line 3</div>
    <div id="line4">This is line 4</div>
    <div id="line5">This is line 5</div>
    <div id="line6">This is line 6</div>
    <div id="line7">This is line 7</div>
    <div id="line8">This is line 8</div>
    <div id="line9">This is line 9</div>
    <div id="line10">This is line 10</div>
    <div id="line11">This is line 11</div>
    <div id="line12" style="height: HEIGHTpx; vertical-align:middle; display: table-cell;">This is line 12</div>
    <div id="line13">This is line 13</div>
    <div id="line14">This is line 14</div>
    <div id="line15">This is line 15</div>
    <div id="line16">This is line 16</div>
    <div id="line17">This is line 17</div>
    <div id="line18">This is line 18</div>
    <div id="line19">This is line 19</div>
    <div id="linelast">This last line</div>
</div>

</body>
</html>
